Tim Cook may as well have made Apple’s new rainbow-hued iPhones the color of mud the way they’re selling.

The iPhone 5C, which retails for a mere $100 less than the faster, sleeker 5S, made up just 27 percent of the gadget maker’s phone sales in September, according to new data released Wednesday by Consumer Intelligence Research Partners.

By contrast, the 5S, which comes with more features, including finger-sensor technology, made up 64 percent of total sales last month.

The remaining 9 percent of sales went to Apple’s iPhone 4S.

Slow sales of the 5C, which comes in white, blue, green, pink or yellow, have also forced Apple to reduce orders with component suppliers and assemblers of the product, The Wall Street Journal reported.

Still, news of the underwhelming 5C sales was largely brushed off by investors amid general cheer over strong sales of the pricier 5S, which come with plumper margins.

“In a vacuum it’s a bad data point, but when you put it in context, the market isn’t as worried,” said Michael Walkley, an analyst with Canaccord Genuity.

Shares of Apple Wednesday closed up 0.5 percent, to $501.11, the sixth straight day of advances.